Method of testing stay bolts



Nov. 23 1926.

. 1,607,621 J. B'. HELLER METH'OD OF TESTING STAY BOLTS Filed Jan. 25, 1924 Patented Nov. 23, 1926.

JESSE B. HELLER 0F OLAREIIDON, VIRGINIA, T0 FLANNERY BOLT COM- PANY, OF PITTSBURGH, EENNSYLVANTA, A CGRPQRATZGH O PENNSYLVANIA.

METHOD 6F TESTING STAY 03128.

Application filed January 25, 1924.

The present invention relates to boiler staybolts having telltale holes therein, and more particularly to boiler staybolts having heads at their outer ends for cooperation with sleeves carried by the outer boiler sheet.

It is customary to inspect the staybolts ii, a boiler at regular intervals, to determine the fractured or broken bolts, and it has been proposed to provide such staybolts with telltale holes in order that, when a bolt be comes fractured or broken, this fact may be made manifest to the inspector by leakage of water from the boiler through its telltale hole.

When a staybolt becomes fractured in service to such an extent that the crack reaches the telltale hole,'water will begin to enter the telltale hole and will pass out through the porous plug which usually closes the mouth of the hole, either in the form of steam or drops of water, and the telltale hole will graduallyfill up with scale formed largely from the deposit left by the water which evaporates in the telltale hole. The deposit left in this manner will accumulate more or less rapidly, depending on the hardness of the water, and thus in time completely close the telltale hole at at least some point therein. On the other hand, if the mouth of the telltale hole is not closed by a plug, or if the plug which wasoriginally placed therein is destroyed or drops out, solid matter may enter the telltale hole from the firebox and obstruct or clog the hole. Even if the telltale hole is closed by a porous plug placed in its mouth, moisture in the combustion gases is liable to enter the telltale hole from the fire-box through the porous plug and condense on the walls of the telltale hole. Since the staybolt is usually made of ferrous metal, this moisture may in time cause a sufficient amount of rust or corrosion on the walls of the telltale hole to prevent it fronii properly functioning. Solid matter in the telltale hole of a bolt from whatever source it may have entered the same, is liable to prevent the proper functioning of such telltale hole. /Vhen an inspection of the staybolts of a boiler is being made, therefore, it is of prime impor tance that all of the telltale holes of the bolts be open and unobstructed throughout their entire length, in order to insure that Serial No. 688,43?

the fractured orbroken bolts may give an indication of their condition by reason of leakage through their telltale holes. The first thing for the inspector to determine, therefore, in making his inspection, is which of the bolts have their telltale hole obstructed. The next step is to drill out such obstructed telltale holes to clear them of the obstructing material. In ordinary boiler construction, the staybolts used may vary in length from six inches to thirty inches. Where there is a variation in bolt length there will usually be a corresponding variation in the length of the telltale holes. In the case of boiler staybolts having heads at their outer ends for cooperation with sleeves carried by the outer boiler sheet, the telltale holes should extend from the inner ends of-the bolts into, but not through, the

headed outer ends thereof because expert ence has demonstrated that boiler staybolts of this type are very liable to fracture adjacent the headed ends thereof. I

The purpose of the present invention is to provide means in the telltale holes of boiler staybolts for cooperation with a drill to indicate to the driller when he has reached the original outer closed end of a telltale hole.

In the drawings there are shown certain preferred embodiments of my invention, it being understood that the drawings do not define the limits of the invention, as changes may be made in the details of construction shown without departing from the spirit of the invention or scope of the appended claim. H

In the drawings c V I t Figure 1 is a view showing in section portions of the inner and outer sheets of a boiler having a plurality of headed staybolts associated therewith.

Figure 2 is a view similar to Figure 1 showing a slight modification.

Referring to the embodiment of the invention shown in Figure 1, the reference numerals 2 and 3 designate portions of the inner and outer boiler sheets and i a series of headed staybolts associated therewith, these staybolts varying in length one from the other. Each of these bolts is provided with a telltale hole 5 extending from the inner end of the bolt axially thereof into, but not through, the head 6 of the bolt.

of each bolt-to form a closure therefor.

In order that solid matter may be prevented from entering the telltale holes of the bolts from the fire-box a porous plug 7 may be placed in the mouth of each telltale hole, which plugs may be removed when it is desired to inspectthe bolts.

Boiler staybolts are usually made of a ferrous metal. When the telltale hole of a bolt becomes obstructed, the obstructing material, for example, boiler scale, may offer greater resistance to drilling than the material of the bolt itself, so that the drill employed for cleaning out such telltale hole should be capable of cutting through any such obstructing material. Consequently, a drill of this kind would be capable of cutting through the head of the bolt itself. In order to indicate to the driller when he has reached the original outer closed end of the telltale hole, I propose to place in the outer closed end of each telltale hole a slug 8 of material which is more resistant to drilling than either the material of the bolt itself or any material which is likely to ob struct the telltale hole. The material which I prefer to employ for this purpose is a tool steel. Such a material will enable a drill to be employed which will cut through any usual obstructing material, such as boiler scale, but which at the same time will not cut through the slug. The slug will form the end wall of the telltale hole with which it is associated and will immediately indicate to the driller when he has reached such end wall by causing the drill to spin around without progressing further into the bolt.

In the modified construction shown in Figure 2, the longitudinal bore which forms the telltale hole 5 of each bolt is drilled throughout the full length of each bolt, including its headed portion, and in order that the telltale hole may be made to terminate within the head 6 of each bolt, and therefore beyond every portion of the bolt which is liable to become fractured, a plug 9 is inserted in the outer end portion of the bore This plug may be made of tool steel so as to perform the same function as the slug 8 in the construction shown in Figure 1, or the plug may be made of a material similar to that of which the body of the bolt is made and a slug of tool steel, or similar hard material, may be placed in the outer end portion of each telltale hole to form the end wall of the hole, as in the construction shown in Figure 1.

If desired, the tool steel employed to form the end wall of the telltale hole of each bolt at the outer end thereof may be a so-called rustless tool steel, that is, a tool steel having small quantities of chromium and nickel alloyed therewith, in order that the end wall of the telltale hole may not become corroded by reason of the condensation. of moisture thereon entering the telltale hole from the lire-box through the porous plug closing the mouth of the telltale hole. This will insure that when an electrical testing implement, such as is disclosed in the co-pending application of Grover R. Greensladc, Serial No. 681,955, filed December 2 1928, is thrust into a telltale hole which is open throughout its length, such implement will make a good electrical contact with the en( wall of the telltale hole.

.Vhile I have mentioned tool steel as a suitable material for forming the end wall of each telltale hole at the outer end thereof, it will be understood that the invention is not limited to the use of this particular material, as any other suitable material which is highly resistant to drilling may be employed for this purpose.

I claim:

The method of testing staybolts having telltale holes therein, con'iprising determining the depth to which the bolt is to be tested, seating a stop at such a depth in the telltale hole of suiiicient hardness to preventthe cutting thereof by a drill, and then drilling out any scale formed in the telltale hole between the open end thereof and the stop, preparatory to inserting the testing tool.

In testimony whereof I have hereunto set my hand.

JESSE B. HELLER. 

